1. Field of the Invention
The present invention relates to a coated polyamide molding product in which strength, rigidity, gripping property, packing and sealing characteristics and vibration cushioning property are compatible by means of coating a soft thermoplastic resin elastomer on the surface of a molding product of polyamide resin having good strength, rigidity and shock resistance.
2. Description of the Related Art
With regard to a compounded molding product by a hard material and a soft material, a compounded molding has been carried out by a combination of materials of the same quality such as hard olefin material and soft olefin material followed by subjecting to a thermal fusion whereby various commercial products have been developed (e.g., Nippon Gomu Kyokai Shi, vol. 69, no. 9, p. 631 (1996) and Purasuchikkusu, vol. 48, no. 3, p. 30 (1997)). In a thermal fusion of different materials, the compatibility between/among the different materials is quite important and, in the case of a combination of the materials of the same quality, the thermal fusion can be done relatively easily. However, there is a disadvantage in a combination of such materials of the same quality that only very limited materials are able to be used and that the field of use is limited as well.
In the meanwhile, there has been a report where a general-purpose elastomer such as thermoplastic elastomer of a styrene type and thermoplastic elastomer of an olefin type is blended with an engineering elastomer having polar groups such as thermoplastic polyester elastomer and thermoplastic polyamide elastomer comprising polyether block amide and the resulting soft material is subjected to a thermal fusion with a hard material such as ABS, polycarbonate, Nylon and PBT (e.g., Japanese Patent Laid-Open No. 9878/1994, No. 11662/1995, etc.).
In such a method, however, there is used a specific soft material where a general-purpose thermoplastic elastomer is blended with a very expensive thermoplastic elastomer of a polyamide type or thermoplastic elastomer of a polyester type. Therefore, the product is an expensive specially-coated molding product and, in addition, a phase separation of the soft material may take place depending upon a combination of blending resulting in a defective part in the molding product and that is not preferred.